Was wondering if I will still be able to get 20mpg with 31x10.50x15 in tires? I got the tracker to get good gas mileage but I found myself buying a spacer lift and body lift. It is a 2001 that is a 5spd.

i get an honest all around 20-21mpg with 235-75-15's (29's) with my '00 w/ my 2.0 5speed w/140,000 miles.

I found with all of the Suzuki's and Trackers I have owned over the years they were all "under tired" with the stock tires (205/75/15 for Trackers) they came with.  My GPS confirmed the difference.  I put Michelin 235/70/15s on my last '02 Tracker and the speedo was dead on with the ground speed indicated with my GPS.   I put Michelin 235/75/15s on my current '02 and my true ground speed is just a little faster than indicated by the speedo (+1-1.5 mph).   I'm a retired fart now and actually find myself cruising down the road at 50MPH regularly.  Yeah, I'm now the guy who use to piss the hell out of me.   No place to be and all day to get there (usually).  I get 25MPG on my trucklet with a 2 Liter and 5spd reguarly and I've even gotten 28MPG on a couple ocassions, but believe me... you wouldn't want to be the poor bastard following me when I was cruising this "conservatively".

Anyway, I'm guessing you will probably end up with a trade off with the larger tires:  more weight to spin but then your speedo will be constantly lying to you about how far you have REALLY gone on a tank of gas too.  My inlaws have a 4 door ZR2 with the V6.  They say they too are getting about 20MPG on it... but then the 215 size tires that come stock on ZR2s are probably under sized as well and giving them false figures as well.

You're going to be traveling just about 4" farther with every rotation of your tires when you mount 31s on your rims.

i get an honest all around 20-21mpg with 235-75-15's (29's) with my '00 w/ my 2.0 5speed.

I forgot to mention after I read the last post that this mpg is WITHOUT trying to conserve.  75-80 on freeway and usually push the skinny pedal more then necessary around town...

My own experience contradicts a bit...

'01, 5 speed, 2.0, 2 door, stock, 116k miles:  I found I got about 2mpg better with the stock 205/75/15 tiger paws than the 215/75/15 bfg at's that I have now.  I think part of it is that the tires are more aggressive and heavier.  My speedo was also dead on with the 205's at 70mph and is now reading slow by about 1.5mph at 70 compared with my gps.  With the 205's my record was 34, but I would regularly get 28-30.  With the 215's my record is 30, and regularly get 26-28.  This is all with conservative driving and my mileage drops about 2mpg in the winter.  I don't think i've ever had a tank below 20mpg even when some four wheeling was mixed in!

you can do the conversions here but i run 31x9.5 swampers on mine with the 2.0L 5spd.  speedo is about 10.5% off, when it shows 100km/h i'm my gps shows 110/111km/h, i will get 415-430 max on the odometer on a full tank to almost sputtering empty, so real mileage maybe 450-470km per tank at the very best, if i'm driving into the wind like yesterday i can barely hold 120km/h actual speed with the pedal on the floor!  in bad wind or very hilly driving the mileage is significantly worse.  that's the stock 4.62 gearing..  now if you had a 31inch tire with more of an a/t or street tread i'm sure the mileage would be a little better..  the lugs on the swampers aren't so aerodynamic!

I went from 215/75/15 stock tires on my 2003 tracker zr2 to 31/9.5/15 with no noticable difference in my milage. I did instal manual locking hubs near the same time which helps some.